Have you tried jumping it with leads to see if it your battery, I was sure it wasn't my battery and it turns out it was, didn't help that the king lead was arking also
Jumped it with X5 today still struggled to start for a good few turns but turned much quicker, try it and see, I feel a right plonker after putting my life on it that it was not the battery
Starts like a dream now as I had the starter motor refurbed anyway cos that was damaged also.....
Good luck mate